Enaminone-Directed Rh(III)-Catalyzed Hydroarylation Reaction of Oxa/azabenzonorbornadienes through C–H Bond Functionalization

Abstract

We report an Rh(III)-catalyzed hydroarylation of oxa- and azabenzonorbornadienes directed by enaminones through C–H activation. The reaction proceeds under mild conditions with broad substrate scope and excellent regioselectivity. Diverse polycyclic products are obtained in high yields. A representative structure was confirmed by X-ray analysis.

Keywords

C–H activation - Rhodium catalysis - Enaminone - Hydroarylation - Oxa/azabenzonorbornadienes

Publication History

Received: 25 July 2025

Accepted after revision: 18 August 2025

Accepted Manuscript online:
19 August 2025

Article published online:
18 September 2025

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• 22b General Procedure for C–H Activation/Hydroarylation (1 mmol scale): Enaminone 1a (175 mg, 1 mmol), [RhCp*Cl₂]₂ (2.5 mol %), AgSbF₆ (15 mol %), NaOAc (1.5 equiv), and dioxazolone 2a (144 mg, 1 mmol) were weighed into a pressure tube, to which was added DCE (10 mL). The reaction mixture was stirred for 24 h at 110 ^°C. Purification was performed by flash column chromatography on silica gel using EtOAc and petroleum ether to afford product 3
• 22c (E)-3-(dimethylamino)-1-(2-((2R)-1,2,3,4-tetrahydro-1,4-epoxynaphthalen-2-yl)phenyl)prop-2-en-1-one (3aa): Reaction Time: 24 h.; viscous oil; 240 mg, 75% yield; ¹H NMR (400 MHz, CDCl₃) δ 7.70 (d, J = 8.0 Hz, 1H), 7.36 (t, J = 7.5 Hz, 1H), 7.33–7.16 (m, 5H), 7.16–7.08 (m, 2H), 5.48 (d, J = 4.5 Hz, 1H), 5.28 (d, J = 12.2 Hz, 1H), 5.27 (s, 1H), 3.21 (dd, J = 8.1, 4.3 Hz, 1H), 2.90 (s, 6H), 2.14–1.95 (m, 2H); ¹³C NMR (100 MHz, CDCl₃) δ 194.5, 154.9, 146.3, 146.2, 142.6, 142.3, 129.4, 127.1, 126.7, 126.51, 126.46, 125.6, 119.1, 118.9, 98.5, 85.4, 79.3, 44.9, 41.7, 38.6, 37.0; HRMS (ESI⁺) m/z calcd for (M + H)⁺ [C₂₁H₂₁O₂N + H]⁺ : 320.1651, found 320.1653